From: Lukas Herbolt <lukas@herbolt.com>
Date: Tue, 10 Mar 2026 12:30:22 +0000 (+0100)
Subject: xfs: Use xarray to track SB UUIDs instead of plain array.
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8da6fd088472f4db6199fb68af6ec87fa26247ca;p=thirdparty%2Fkernel%2Flinux.git

xfs: Use xarray to track SB UUIDs instead of plain array.

Removing the plain array to track the UUIDs and switch
to xarray makes it more readable.

Signed-off-by: Lukas Herbolt <lukas@herbolt.com>
[cem: remove unneeded return from xfs_uuid_unmount]
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
---

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 9c295abd0a0ac..265011333904d 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -44,17 +44,36 @@
 #include "xfs_healthmon.h"
 
 static DEFINE_MUTEX(xfs_uuid_table_mutex);
-static int xfs_uuid_table_size;
-static uuid_t *xfs_uuid_table;
+static DEFINE_XARRAY_ALLOC(xfs_uuid_table);
+
+static uuid_t *
+xfs_uuid_search(
+	uuid_t		*new_uuid)
+{
+	unsigned long	index = 0;
+	uuid_t		*uuid;
+
+	xa_for_each(&xfs_uuid_table, index, uuid) {
+		if (uuid_equal(uuid, new_uuid))
+			return uuid;
+	}
+	return NULL;
+}
+
+static void
+xfs_uuid_delete(
+	uuid_t		*uuid,
+	unsigned int	index)
+{
+	ASSERT(uuid_equal(xa_load(&xfs_uuid_table, index), uuid));
+	xa_erase(&xfs_uuid_table, index);
+}
 
 void
 xfs_uuid_table_free(void)
 {
-	if (xfs_uuid_table_size == 0)
-		return;
-	kfree(xfs_uuid_table);
-	xfs_uuid_table = NULL;
-	xfs_uuid_table_size = 0;
+	ASSERT(xa_empty(&xfs_uuid_table));
+	xa_destroy(&xfs_uuid_table);
 }
 
 /*
@@ -66,7 +85,7 @@ xfs_uuid_mount(
 	struct xfs_mount	*mp)
 {
 	uuid_t			*uuid = &mp->m_sb.sb_uuid;
-	int			hole, i;
+	int			ret;
 
 	/* Publish UUID in struct super_block */
 	super_set_uuid(mp->m_super, uuid->b, sizeof(*uuid));
@@ -80,30 +99,17 @@ xfs_uuid_mount(
 	}
 
 	mutex_lock(&xfs_uuid_table_mutex);
-	for (i = 0, hole = -1; i < xfs_uuid_table_size; i++) {
-		if (uuid_is_null(&xfs_uuid_table[i])) {
-			hole = i;
-			continue;
-		}
-		if (uuid_equal(uuid, &xfs_uuid_table[i]))
-			goto out_duplicate;
-	}
-
-	if (hole < 0) {
-		xfs_uuid_table = krealloc(xfs_uuid_table,
-			(xfs_uuid_table_size + 1) * sizeof(*xfs_uuid_table),
-			GFP_KERNEL | __GFP_NOFAIL);
-		hole = xfs_uuid_table_size++;
+	if (unlikely(xfs_uuid_search(uuid))) {
+		xfs_warn(mp, "Filesystem has duplicate UUID %pU - can't mount",
+				uuid);
+		mutex_unlock(&xfs_uuid_table_mutex);
+		return -EINVAL;
 	}
-	xfs_uuid_table[hole] = *uuid;
-	mutex_unlock(&xfs_uuid_table_mutex);
 
-	return 0;
-
- out_duplicate:
+	ret = xa_alloc(&xfs_uuid_table, &mp->m_uuid_table_index, uuid,
+				xa_limit_32b, GFP_KERNEL);
 	mutex_unlock(&xfs_uuid_table_mutex);
-	xfs_warn(mp, "Filesystem has duplicate UUID %pU - can't mount", uuid);
-	return -EINVAL;
+	return ret;
 }
 
 STATIC void
@@ -111,21 +117,12 @@ xfs_uuid_unmount(
 	struct xfs_mount	*mp)
 {
 	uuid_t			*uuid = &mp->m_sb.sb_uuid;
-	int			i;
 
 	if (xfs_has_nouuid(mp))
 		return;
 
 	mutex_lock(&xfs_uuid_table_mutex);
-	for (i = 0; i < xfs_uuid_table_size; i++) {
-		if (uuid_is_null(&xfs_uuid_table[i]))
-			continue;
-		if (!uuid_equal(uuid, &xfs_uuid_table[i]))
-			continue;
-		memset(&xfs_uuid_table[i], 0, sizeof(uuid_t));
-		break;
-	}
-	ASSERT(i < xfs_uuid_table_size);
+	xfs_uuid_delete(uuid, mp->m_uuid_table_index);
 	mutex_unlock(&xfs_uuid_table_mutex);
 }
 
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index ddd4028be8d6b..d964bae096ef6 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -346,6 +346,9 @@ typedef struct xfs_mount {
 
 	/* Private data referring to a health monitor object. */
 	struct xfs_healthmon __rcu	*m_healthmon;
+
+	/* Index of uuid record in the uuid xarray. */
+	unsigned int		m_uuid_table_index;
 } xfs_mount_t;
 
 #define M_IGEO(mp)		(&(mp)->m_ino_geo)